Press brake training helps build a foundation for success

Figure 1: Most employees in Robbins Manufacturing’s press brake department recently underwent in-depth training that covered not only how to operate a machine, but also the reasoning behind those procedures.

During a given day, the 17 press brake technicians in Robbins Manufacturing’s bending department form an impressive range of materials, on a range of machines—from 20-gauge to 1.25-inch-thick mild steel, bent on equipment from a 55-ton electric brake to a 320-ton hydraulic system (see Figures 1 and 2).

By the end of the year, the company expects to install a new press brake with automatic tool change capability. The controller downloads programs, and the system’s mechanization automatically sets up the punches and dies for a job. And thanks to sensors that detect the bend angle in real time, the first part should be a good part. An operator should be able to perform a job consisting of, say, five pieces, then another job of a dozen workpieces, and so on, with mere seconds of changeover time in between. Managers expect the new technology to really help their efforts to reduce batch sizes, to ensure workpieces reach the weld cells at the right time. No one wants a welder waiting around for a missing component.

Here’s the rub: The Fall River, Wis., contract fabricator plans to put one of its most talented, experienced operators on the new press brake. At the same time, the shop has invested in cross-training. The company has worked with Madison Area Technical College and the Fabricators & Manufacturers Association International® (FMA) to provide classroom training on various topics. This includes a comprehensive certificate program on the intricacies of press brake operation.

Some may purchase a new machine tool to deal with the lack of skilled labor available. It’s not an ideal situation; managers are just adapting to a business reality. The people at Robbins, though, are tackling the skilled-labor crisis a little differently.

A Skilled, Adaptable Technician

The art of improvement in manufacturing often involves identifying a constraint, discovering why it’s a constraint, then devising ways to eliminate it. Robbins enjoyed a busy time earlier this year, but as capacity levels increased, inefficiencies became glaringly apparent, especially in bending. The press brake department needed to increase its throughput.

The problem, sources said, was that certain operators learned on specific machines and became specialists on that equipment. The company has different brands of press brakes, and each has its own control-interface idiosyncrasies—nothing dramatic, but just enough to throw off throughput goals on a busy day (see Figure 3).

“We were struggling with the everyday logistics of running the shop,” said Eric Parks, plant manager. “When people were sick or on vacation during a busy time, we ran into constraints that seemed to be avoidable if we had training.”

Up until this point, Robbins’ training regimen had been mostly hands-on. A new employee would shadow an experienced operator and be trained to run a range of products on one machine. But that hands-on training didn’t necessarily cover why a certain forming program worked the way it did. Knowing the reasoning behind forming would give an operator a good foundation for learning how to operate every brake on the floor.

Robbins employs press brake operators in their 20s, 60s, and every age and experience level in between. The company tends to hire brake operators based in part on their blueprint reading capability. Operators may have experience in other trades, be it construction or carpentry, but if they can read a blueprint, managers figure these employees have a good foundation for learning the sheet metal bending craft.

Figure 2: Robbins Manufacturing’s press brake technicians form a big variety of materials, from 20 gauge to 1.25 in. thick, from tight radii to profound-radius and bump bends.

“We generally taught our operators how to bend a family of products,” said Travis DeBussey, fabrication manager. “They understand how to make a group of parts at a specific machine. And in the past, unfortunately, that’s where we’ve stopped. With experience, they evolve to the next step and start to visualize a new setup, so they can bend a part that they’ve never seen before.” But he added that, until now, the company hadn’t offered formal classroom training.

A Common Language

Technical aptitude—knowing what has to be done—hasn’t been a problem. Instead, it was about the why, and about communicating that reasoning in a common language, be it bend radius, bend angle, bend allowance, bend deduction, tangent point, outside setback, or any other term in sheet metal bending. No matter the operator, press brake make and model, or company, everyone should speak the same bending language.

Many aspects of brake setup have become automated. Software can calculate the bend allowance and deduction and, ultimately, determine the correct die opening and punch for specific bends. But why is that die opening the way it is for a particular job? Why is the minimum flange length this measurement for this workpiece? Why is the radius pitch (the distance between hits made when bump-bending a large radius) specified this way? Why exactly does a bend become “sharp” at 63 percent of the material thickness, and why can’t you put a sharper radius in the bend without digging a ditch into the bend line?

“We’ve always had press brake operators, turret press operators, and laser operators,” said Parks. “We’re starting to migrate toward having fabricators.”

The ultimate goal is to have a flexible workforce capable of operating any machine in the fabrication area. So managers reached out to Madison Area Technical College. MATC’s outreach program, through grants, partially funded Robbins’ training initiative, which included a press brake operator certificate program from FMA. As part of this program, Steve Benson, president of Salem, Ore.-based ASMA LLC (and frequent contributor to this magazine), conducted a training program over two weekends in August. Several days focused on laser and punch press operation, but most instruction focused on the press brake.

The 20-person class had many of the company’s brake operators, but also other machine operators, including several turret operators who had never operated a press brake before. Most attendees passed the certificate course’s press brake exam with flying colors.

This isn’t to say the exam, or the training course, is a cakewalk. As Parks explained, even the shop’s most experienced operators learned something new. “Some of the more experienced people were reluctant because they’ve been [operating a brake] for a long time, and they understand how to do it. But they picked up on quite a few things, including some of the basic foundations, including some of the math that showed why they do what they do.”

So why is the “why” so important, especially if software gives operators the answer?

As sources explained, it comes back to communication. For instance, some customer prints at Robbins specify a flange length from the edge (formed or cut) to the bend line. Other prints specify a flange length between the edge and the inside surface of the flange. On a tight radius in thin material, the difference between these two measurements can be minimal, but for a profound-radius bend (with inside radius 10 times the material thickness or more) or even a, say, 0.25-in. radius on 14-gauge sheet, the difference can have an effect on the finished part. Before the class, they all knew how to measure flanges correctly. But now everyone uses the same terms, which helps prevent miscommunication and, most important, any wasted time that miscommunication creates.

During the day an engineer from the front office may consult with key brake personnel about a quote. As sources explained, the line of communication between the front office and floor has remained clear, especially for a 210,000-square-foot plant with 247 employees.

Figure 3: Robbins Manufacturing has multiple press brake brands, each of which has a different control interface. Managers wanted to cross-train employees on all equipment, and this was where in-depth training on bending fundamentals helped.

“Considering the size of our shop, we have an open line of communication with our engineers to discuss the best way to manufacture a part,” DeBussey said, adding that here, too, establishing a common language—thanks to the recent training—has helped.

Smaller Batches, Shorter Lead-Time

During a typical day in the press brake department, the brake lead, Dan Schumacher, is given a series of jobs and due dates, and he works to schedule those jobs in a sequence that eases changeovers between jobs. Those changeovers have only grown more frequent in recent months. In a quest for efficient part flow to welding, the shop has cut batch sizes in half. This means it takes less time for all parts of a subassembly to reach the weld station. The smaller the batches, the closer a shop gets to kit-based part flow.

“The hardest part of my job is the short lead-time,” Schumacher said. “Otherwise, the department runs itself. I’m lucky. I’ve got a very good crew.”

With all those changeovers comes many part sizes and thicknesses, and to maintain that flow requires knowledge of setups and, not least, required tonnages. “We run anything from 20 gauge to 1.25 inch thick,” Schumacher said. “Although the brakes vary from 55 ton all the way up to 350 tons, the same fundamentals apply.”

This includes the tonnage a job requires, expressed in the training class as: Tonnage per inch for air forming = {[(575 × Material thickness2)/Die width]/12} × Material factor. Common 60,000-PSI-tensile-strength AISI 1035 cold-rolled steel has a material factor of 1. That’s the baseline. If you have a material with a maximum tensile strength of 120,000 PSI, you divide that by 60,000 to get a material factor of 2. Finally, to get the total tonnage needed for the job, you multiply the total tons per inch by the length of bend.

That formula shows how certain factors affect overall tonnage requirements, sometimes dramatically. Note that material thickness is squared. A little more thickness requires a lot more bending pressure. The same thing goes for the length of bend.

According to sources, technicians have known how to work within machine- and tooling-specific tonnage limitations. But thanks to the classroom work, everyone now understands a standard formula, and everyone is on the same page. In this respect, the math is the common language.

Knowledge and Technology

About 10 percent of Robbins’ shop floor workforce attended the class, and at this writing, about 5 percent of the workforce is fully cross-trained on both cutting and bending equipment. Within the next year, managers hope that every class attendee will be cross-trained and productive on all the cutting and bending equipment in the fabrication shop.

On top of this, by the end of this year the fabricator will have installed a new Amada press brake that has automatic tool change. As sources explained, the shop’s founder, Greg Robbins, drives the equipment investment effort and involves key shop personnel in the decision. In choosing to go with changeover automation—which also has real-time angle detection, potentially reducing downtime between jobs to mere seconds—their point wasn’t to overcome the challenges of finding good people. Instead, their point was to give good people the tools they need to be successful. Those tools include both technology and, perhaps most important, knowledge.

“There is so much value in this knowledge,” DeBussey said. “There are all sorts of things in school that they just don’t teach people anymore. We teach them enough to do the job, but they really don’t have any knowledge why they’re doing it. They can run a brake. They can make a part to print. The why is lost, and I think that type of knowledge gives them a sense of pride, and makes them a better operator.”